It's well established that vote anonymity is an important part of representative democracy (discussed elsewhere on this site).

I was listening to 538 podcast today, and they were discussing phone polling and specifically, how different countries have different measured level of trust that people are willing to give when a person asks their political opinions and choices on the phone.

At which point, the idea occurred to me - someone can actually figure out who people voted for by using phone polling (either take a legitimate poll's individual level data dump - assuming they are dumb enough to store per-phone call data - or for the slightly more devious, take a phone directory that has names, call people pretending to be doing a legitimate poll, and instead simply record name, # and who they said they voted for/would vote for).

Question: did something like either of those 2 scenarios ever happen (that we know of?)

If a person tells someone who they voted for, is that really being 'outed'?
– user1530Dec 13 '16 at 5:54

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You seem to be asking for evidence of a public release of raw poll data leading to public de-anonymizing. Are you sure there is an meaningful anonymizing step in most polls? Sounds like melienial angst: "I told a bunch of strangers something personal, what if people find out what it was?"
– user9389Dec 13 '16 at 6:10

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@blip If the person tells with the assurance that the information is confidential, yes, it is outing. Imagine someone telling his best friend (or worse, his doctor) about his illness after asking discretion, only to find out that the best friend or doctor is publicly giving away that info.
– SJuan76Dec 13 '16 at 9:34

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This is a common concern. I think I have read it in almost every survey methods book I have ever read.
– indigochildDec 13 '16 at 16:36

Yes -- all the time. In fact, there are entire organizations that almost exclusively do this type of polling. They'll ask for a particular voter, matched to publicly available voter registration lists, and ask that voter who they voted for or if they intend on voting for particular candidates. They'll record that data on the individual level and produce a data product based on that. Nearly every major political campaign does this as well as part of a canvassing or field program.

Does this "out" or reveal how people voted, therefore compromising a voters right to ballot secrecy.

Absolutely not, the voter is not obligated to provide any information to the pollster, or even accurate information to the pollster and the pollster has no way of knowing how the voter actually voted. In fact, even if the voter gave a truthful accounting of who they intended to voter for on the day/time of the poll, opinions shift and change over time.

I don't think you're really addressing the question. The question is not whether this violates the confidentiality of a person's vote, the question is how confident a person can be that they can give an honest answer to a pollster and not have that information misused.
– AcccumulationJan 7 '19 at 23:03

Polling doesn't ask every single voter and had the inherent problem of selection bias - at least some voters refuse to answer or don't have a reachable phone. So we don't actually know how likely someone is to vote for the same person after they've claimed to do so on the day after the vote.
– JonathanReezMay 9 '19 at 15:01